Oven structure



A. E. GRAPP ovEN STRUCTURE Dec. 16, 1930.

Filed July 16, 1928 2 Sheets-Sheet l Dec. 16, 1930. A, E, GRAPP1,785,079

OVEN STRUCTURE Filed July 16, 1928 2 Sheets-$heet 2 UNE highly Patna-anec. 16,1930 b ALBERT E. GBAPP, 0I' HINNEA-POLIS, MINNESOTA OVENSTRUCTURE Application nled July 16,

This invention relates toovens capable of wide, general use butespecially adapted for baking a plurality of articles.

It is an object of my invention tov provide a eiiicient oven which maybe heated by any suitable source, such as electricity, which will haveincorporated therein means for causing an article or a plurality ofarticles to be evenly subjected to the same intensity of heatl fromevery side, thereby assuring very nearly perfect baking of said articleor articles.

Another object of my invention is to pro- .vide in oven structure,mechanism for holding a plurality of articles for baking and for causingsaid articles to be moved in a circular path within said oven, whilerevolving independently, as they are moved through said circular path,thereby causing said articles to be uniformly subjected on all sides tothe same intensity, or intensities of heat. l

More specifically it is an object to provide oven structure having acarrier for supporting articles to be baked, which carrier is movedthrough a circular path and'simultaneously rotated by circular path.

A further object is to provide a baking oven of compact assembly havinga carrier for articles disposed therein and provided with a readilyremovable top which constitutes the body of the oven, whereby the ovenmay be readily assembled and whereby the interior of the oven may bequickly and easily exposed for cleaning, repair or installation of newparts. These and other objects and advantages of the invention will beapparent from the following description made in connection with theaccompanying drawings, in-which like reference characters refertosimilar parts throughout the several views and in which,

Fig. 1 is a front elevation of a commercial embodiment of my improvedoven equipped its movement through the with electrical heating elements;

Fig. 2 is a vertical section 2-2 of Fig. 1;

Fig. 3 is a plan view with some parts broken away showing theconstruction of my carrier and the mechanism for causing independtakenon the line 1928. Serial No. 292,971.

ent rotation of the several or article holders;

Fig. 4 is a vertical section taken on the line o ig. 3; and

Fig. 5 is an electrical diagram showing one manner in which theelectrical heating units msy be connected with the line.

t will be understood that while th'e following specification describes acommercial embodiment of my invention, especially adapted for the bakingof bread and heated by electricity, that my invention is equallyapplicable on all types of ovens regardless of the source of heatutilized or the particular purposel for which the oven is designed.

The embodiment of my invention illus'- trated includes a largesubstantially rectan ular baking chamber comprising a base and a top T,said base, ported on a plurality made up of inner and outer metallicplates 7 and 8 respectively, between which is interposed a heavy packingof some suitable heat insulating material, suchas magnesia block,mineral wool or the like. The upper edges of base B are provided with ustanding flanges 9 which support the to T 0 the heating chamber. The topTis of oX-shape, open at its lower end and havin front, rear, top andside walls, made up o inner and outer shells 10 and 11 respectivelybetween which is interposed a thick layer of suitable heat insulatingmaterial, such as mineral wool. The front wall is provided with a rectanular door opening .having a suitable beveled frame 12 and a any suitabletype is removably mounted in said doorway as shown being hinged at oneof its vertical edges and having a suitable lock or latch 14 at itsopposite vertical edge. The upstanding lianges 9 of the base B areprovided with vertically disposed lap stri s 15 adapted to overlap thelower edges of t e removable top T, to assist in securing the top inoperative position. I prefer to provide a strip of suita le packingmaterial 16 between the abutting edges of the topv and the upstandingBange 9 to seal the joint between carrying elements as shown, beingsupof legs 6, and being said members and prevent loss of heat. The B areprovided with angle top T and base heavy insulated door 13 ofv strenhening the structure of the oven and also or improving the appearance ofthe device.4 The vertical edges of the top T are also provided withangle stri s 18 projecting beow the lower edges of t e top and adaptedto overla the vertical ed es of base B and be secure Vthereto by suitale means, such as the screws 18a.

Suitable means for heating the baking chamber is provided and in theembodiment of the invention illustrated, comprises a plurality ofelectrical heating elements E, which may be of the type disclosed in myU. S. Patent No. 1,406,372, issued Feb. 14th, 1922, each com rising anelongated bar 19 constructed of i-electric material and having woundthereon two companion heating coi s 20 and 21 wound in substantiallyparallel arrangement and connected to appropriate terminals 22 at thetwo ends of bar 19. As shown in the drawings, the heating elements E aredisposed withln the baking chamber extending at right angles to thefront and rear sides thereof and one series of said units are disposededgewise in the lower portion of the eating chamber and may besupgiorted by rods 23 traversing the side walls o the oven, while asecond set of said elements are disposed in the upper portion of thebaking chamber with their wider surfaces horizontal and in substantiallyparallel relation with cach other, and said upper series may besupported upon rods 24 traversing the upper portions of the side wallsof the oven.

A switch box is shown as supported from a bracket 25a secured to oneside of the base B, said switch box being disposed in spaced andadjacent relation to one of the side walls of the oven. A pair ofsuitable electric switches 26 and 27 for controlling the circuitsthrough the upper and lower series of heating elements respectively aremounted in switch box 25 and an electric light 28 is extended into thebaking chamber connected with a suitable electrical socket 29 secured tothe outer side of the oven wall adjacent switch box 25. A suitablethermostatic circuit breaker, indicated by the numeral 30 is extendedinto the bakinor chamber from the above referred to side of the oven andis electrically connected to break all circuits through the upper andlower heating elements when the temperature within the baking chamberexceeds a predetermined degree.

Mounted within the baking chamber and rigidly secured to the approximatecenter of the base B, I provide a tubular vertical post 31, to the upperend of which is rigidly secured or integrally formed a relatively largestationary gear 32. A carrier frame 33, yillustrated as of spiderconstruction is concentrically mounted above stationary gear 32, beingrigidl fixed to the upper end of shaft 34,- said sha t extending throughthe tubular ost 31 and through the base of the oven and) projecting forsome distance therebelow. A gear 35 is fixed to the lower end of shaft34 which gear is meshed with a driving pinion 36 fixed to the upperportion of a short Vertical shaft 37, as shown, said shaft having oneend thereof journa-led in a bearing 38, fixed to the bottom of base Band having its lower end journaled in a bearing 39 fixed to a shelf 40which is supported in any suitable manner below the base B. A suitableelectric motor M is mounted on shelf 40 and has its armature shaftprovided with .a worm 41 which is in mesh with a worm gear 42 fixed toshaft 37. A slip clutch S of any suitable type is provided in thearmature shaft`- of motor M. Obviously, the motor M will drive the shaft34 of the carrier frame at a relatively low rate of speed, causing saidcarrier frame to revolve within the central portion of the bakingchamber. The spider carrier frame 33 is shown as provided with aplurality of circumferentially arranged and vertically disposed sleeves33a and in each of said sleeves 33a a carrier or holding element 43 isrotatably mounted, each carrier consisting, as shown, of a shallow panrigidly secured to a depending vertical shaft 44, said. shaft extendingthrough one of said sleeves 33a and projecting below the lower endthereof and having a planetary gear 45 fixed to said projecting portionof shaft 44, and the planetary gears 45 of the several carrier elementsare in constant mesh with the large stationary gear 32 and obviouslywill cause the several carrier elements to be independently rotated bythe movement of the spider frame 33.

Since the embodiment of the invention illustrated is especially intendedfor the bale ing of bread, and as such requires that the baking chamberbe maintained at a high temperature, it has been found that some type ofthrust bearing for the carrier shaft 34, which will withstand said hightemperatures, is desirable. After considerable experimenting I havefound that a thrust bearing 46 of graphite composition having a tubularbody and a iianged upper end fulfills all requirements and may be easilyinserted in a suitable socket formed in the upperA portions of thesleeves 33a. Likewise,' I prefer to use a similarly shaped and similarlyconstructed graphite thrust bearing 47 (see Fig. 4) in the upper end ofthe tubular post 31. A disc covering`48 of suitable heat insulatingmaterial (see Figs. 3 and 4) is preferably mounted above spider frame 33and is adapted to diffuse the radiation of heat from the lower series ofheating elements E and to cause the heat to be distributed outwardlytoward the vertical walls of the heating cham ber. This, to aconsiderable measure, prevents the center of the baking chamber frombeing maintained at a much higher temperature than the space adjacentthe walls.

ln Fig. 5 the electrical circuits for the heating elements, motor, lightand thermostatically operated circuit breaker are diagramed. The line ormains are indicated by the numerals 49 and 50 respectively and the light28, motor M and thermostatically operated circuit breaker 30 areconnected in circuit with the mains ahead of switches 26 and 27. As saidswitches are identical in construction, only one thereof is illustrated.and will be described. As illustrated, this switch has four fixedcontacts RL, M, G, and L. The contact RL is connected to the main 50 andto one of the contacts 22 of the heating wire 20. The contact M isconnected in multiple by a wire 51 to the two contacts 22 at theopposite end of bar 19, one of said contacts being connected with thecompanion wire 21 and one being connected to the companion wire 20. Thecontact G is connected with the left hand terminal of the wire 2l andthe contact L is connected with the lead main 49. rotary type andconnections across the contacts RL, M, G and L may be made as followsWith the movable element of the switch in one position, contacts RL andG and M and L will be respectively connected and this` will close thecircuit across the line as follows z- Current will flow through the lead49 through both companion wires 20 and 21 connected with said lead inmltiple and back to the line in multiple. This will connect in multipleall of 011e series of heating elements and will give the greatestpossible heat.

When the movable element of the switch is in the next position, thecontact M will be connected with the contact L and the contact L will bealso connected with the contact G. Current will then flow through thelead 49 through wire 51, through companion wire 20 and back to the linethrough the main 50 and the companion wire 21 will be shunted acrosssaid circuit. No current will pass through companion wire 21. vThiscircuit gives approximately half the amount of heat of the multiplecircuit previously described and will be known as the intermediateheating circuit. With the movable element of the switch in next or thirdposition, the contact G will be connected with the Contact L and thecurrent will flow from the main 49 through the companion wire 21 andback through the companion wire 20 and through the main 5 0. Obviously,this connects the two companion coils 20 and 21 in series and gives aless amount of heat than either of the circuits previousl described..

If esired, of course, the top and bottom series of heating elements maybe connected Switches 26 and 27 are of thi-l together and operated by asingle switch, but where electricity is used as a source. of heat Iprefer to provide separate switches for each series of heating elements.

Operation The operation of my oven may be briefly described as followsThe bread or other articles to be baked or heated are placed in theseveral pans of carriers 43 and the switches 26 and 27 are thrown inpositions to control the proper temperature within the baking chamber.The circui through the motor is then closed and the spider carrier frame33 is slowly revolved by its driving connection with motor M. Themovement of frame 33 about the axis of shaft 34 causes planetary gears45 to be driven, giving an independent rotation to each of the carrierelements 43. Each article carried therefor travels through a circularpath in the central portion of the baking chamber and moreover rotatesindependently throughout its travel through said path, thus subjectingevery side of the article to the different intensities of heat withinthe oven. It is a well known fact that it is impossible to manufacturean oven having a uniform temperature throughout the baking chamber. Thespace adjacent the door of the oven is always maintained at a lowertemperature than the space adjacent the rear side and the center of theovenis usually hotter than the space adjacent the walls of the oven.With my oven it will be seen that the articles to be baked arecontinuously moved through the different positions of the baking chambertraveling in a circular path. If the several carrier elements 43 are notindependently rotated, one portion or side of each article would con--stantly face toward the axis of the carrier independently rotated at afaster speed than the speed of the carrier frame and consequently allsides or vertical surfaces of the articles are subjected to practicallyever temperature within the oven. It will thus be seen'that the articlesmay be very nearly perfectly baked in my oven. The thermostaticallyoperated circuit breaker 30 controls the mean temperature within theoven and the light 28 illuminates the contents of the oven.

The novel construction of the baking chamber enables the top to bereadily .removed by disconnecting the light, thermostatic circuitbreaker and connection withthe upper heating series, it being onlynecessary: to loosen screws 18a and lift the top from its engagementwith the lap strips 15. The pro-y jecting angle strips 18 covering thevertical edges lof top T overlap the short vertical edges of the baseand fit between the ends of ad- 1t is, of

bearings and 47, if the same shouldY be necessary or clean or repair theother working arts. The box-like to of the baking chamr may also beeasily c eaned after removal. The two part removable structure is also agreat convenience for shipping and assembling the device, as the carrieror holder structure may be separately shipped and installed at thedestination point and thereafter the box-like top T may be quicklysecured to base B. It will, of course, be seen that my invention isequally applicable to ovens of .all types, whether heated by electricityor other means. It will also be understood that while I have illustrateda plurality of circumferentially disposed carrier elements, that one ormore of said carrier elements may be utilized eccentrically disposedwith reference to the pivot for the `carrier frame and connected forindependentrotation during the movement ot' said carrier frame.

It will be further understood that various changes may be made in theform, details, arrangement and proportions of the parts withoutdeparting from the scope of applicants invention.

What is claimed is:

1. An oven comprising a baking chamber, a stationary gear disposed abovethe bottom of said chamber, a carrier frame above said gear mounted forrotation on an aXis concentric with said gear and having a dependingshaft projecting through the base of said chamber, a pluralityof'carrier elements circumferentially arranged about the axis of saidcarrier frame and rotatably mounted in said carrier frame, said carrierelements having planetary gears in mesh with said stationary gear, meansdisposed below said chamber for driving said shaft to cause rotation ofsaid frame and in co-operation with said stationary gear to causeindependent rotation of said carrier elements at a high rate of speed,and heating elements in said chamber.

2. An oven comprising an enclosed baking chamber, a carrier elementmounted for movement in a circular path within the medial portion ofsaid baking chamber, said carrier element having an article holdingmember at the upper portion thereof, said baking chamber having anunobstructed portion above said carrier element, a stationary gearconcentric with the path of said carrier element, said carrier elementincluding a vertical shaft rotatively mounted, a relatively smallplanetary gear fixed to the lower portion of said shaft and meshed withsaid stationary gear, and means for moving said carrier element throughsaid circular path.

3. An oven comprising an unobstructed baking chamber, a frame spacedfrom the bottom of said baking chamber, a relatively large stationarygear Xed to said frame, a carrler frame above said stationary gear r0-tatively mounted on an axis concentric with said gear, a series ofcircumferentially arranged carrier elements rotatively mounted in saidframe on axes parallel to the axis of said frame, said carrier elementshaving article holding members disposed above said carrier frame, andhaving relatively small planetary gears below said carrier frame in meshwith said stationary gear, and heating elements in the lower portion ofsaid chamber below said stationary gear.

4. The structure set forth in claim 3, and a heat delecting memberpositioned substantially centrally of said chamber and below saidarticle carrying member and adapted to direct forwardly movingconvection currents of heated air outwardly toward the walls of saidchamber.

5. An oven comprising a rectangular base having an upstanding supportingflange provided with vertical corner edges, a box-like top having anopen lower end supported on the upstandingllange of said base, a seriesof heating elements supported from said base and a support for articlesto be baked mounted on said base and extending a considerable distancethereabove, said top having vertical angle strips at its cornersprojecting below its lower edge, said projecting portions being adaptedto engage the corner edges of the iange of said base, and means forsecuring said projecting angle strips to the Acorner edges of said base.

In testimony whereof I aix my signature.

ALBERT E. GRAPP.

